This operation was the second major operation in Fallujah. Earlier, in April 2004, coalition forces fought the First Battle of Fallujah in order to capture or kill insurgent elements considered responsible for the deaths of a Blackwater Security team. When coalition forces fought into the center of the city, the Iraqi government requested that the city's control be transferred to an Iraqi-run local security force, which then began stockpiling weapons and building complex defenses across the city through mid-2004.[19] The second battle was the bloodiest battle of the entire Iraq War,[20] and is notable for being the first major engagement of the Iraq War fought solely against insurgents rather than the forces of the former Ba'athist Iraqi government, which was deposed in 2003.

Within days, U.S. Marine Corps forces launched Operation Vigilant Resolve (4 April 2004) to take back control of the city from insurgent forces. On 28 April 2004, Operation Vigilant Resolve ended with an agreement where the local population was ordered to keep the insurgents out of the city.[19] The Fallujah Brigade, composed of local Iraqis under the command of a former Ba'athist officer named Muhammed Latif, took control of the city.[23]

Insurgent strength and control began to grow to such an extent that by 24 September 2004, a senior U.S. official told ABC News that catching Abu Musab al-Zarqawi, said to be in Fallujah, was now "the highest priority," and estimated his troops at 5,000 men, mostly non-Iraqis.[24]

Before beginning their attack, U.S. and Iraqi forces had established checkpoints around the city to prevent anyone from entering the city, and to intercept insurgents attempting to flee.

In addition, overhead imagery was used to prepare maps of the city for use by the attackers. American units were augmented by Iraqi interpreters to assist them in the planned fight. After weeks of withstanding air strikes and artillery bombardment, the militants holed up in the city appeared to be vulnerable to direct attack.

U.S., Iraqi and British forces totaled about 13,500. The U.S. had gathered some 6,500 Marines and 1,500 Army soldiers that would take part in the assault with about 2,500 Navy personnel in operational and support roles.[5] U.S. troops were grouped in two Regimental Combat Teams: Regimental Combat Team 1 comprised 3rd Battalion/1st Marines, 3rd Battalion/5th Marines, Naval Mobile Construction Battalion 4 and 23 (Seabees) as well as the U.S. Army's 2nd Battalion/7th Cavalry. Regimental Combat Team 7 comprised the 1st Battalion/8th Marines, 1st Battalion/3rd Marines, the U.S. Army's 2nd Battalion/2nd Infantry,2nd Battalion/12th Cavalry and 1st battalion 6th field artillery.[25] About 2,000 Iraqi troops assisted with the assault.[5] All were supported by aircraft U.S. Marine and U.S. Army artillery battalions and USSOCOM Sniper Elements.

The 850-strong 1st Battalion of the Black Watch was ordered to help U.S. and Iraqi forces with the encirclement of Fallujah.[26] As part of Task Force Black, D Squadron of the British SAS prepared to take part in the operation, but British political nervousness about the possible scale of casualties stopped any direct UK involvement in the ground battle.[27]

In April, Fallujah was defended by about 500 "hardcore" and 1,000+ "part time" insurgents. By November, it was estimated that the numbers had doubled.[28] Another estimate put the number of insurgents at 3,000; however, a number of insurgent leaders escaped before the attack.[29]

Fallujah was occupied by virtually every insurgent group in Iraq: al-Qaeda in Iraq (AQI), Islamic Army of Iraq (IAI), Ansar al-Sunna, Army of Mohammed (AOM), the Army of the Mujahedeen and the Secret Islamic Army of Iraq. Three groups, (AQI, IAI and the National Islamic Army (1920 Revolution Brigade)) had their nationwide headquarters in Fallujah. An estimated 2,000 insurgents were from the Army of Mohammed (made up of ex Fedayeen Saddam fighters), Ansar al-Sunna and various smaller Iraqi groups.[30]

The Iraqi insurgents and foreign mujahadeen present in the city prepared fortified defenses in advance of the anticipated attack.[19][31] They dug tunnels, trenches, prepared spider holes, and built and hid a wide variety of IEDs.[19][31] In some locations they filled the interiors of darkened homes with large numbers of propane bottles, large drums of gasoline, and ordnance, all wired to a remote trigger that could be set off by an insurgent when troops entered the building. They blocked streets with Jersey barriers and even emplaced them within homes to create strong points behind which they could attack unsuspecting troops entering the building.[32] Insurgents were equipped with a variety of advanced small arms, and had captured a variety of U.S. armament, including M14s, M16s, body armor, uniforms and helmets.[32]

They booby-trapped buildings and vehicles, including wiring doors and windows to grenades and other ordnance. Anticipating U.S. tactics to seize the roof of high buildings, they bricked up stairwells to the roofs of many buildings, creating paths into prepared fields of fire which they hoped the troops would enter.[32]

Intelligence briefings given prior to battle reported that coalition forces would encounter Chechen, Filipino, Saudi, Libyan, and Syrian combatants, as well as native Iraqis.[33]

Meanwhile, most of Fallujah's civilian population fled the city, which greatly reduced the potential for noncombatant casualties.[32] U.S. military officials estimated that 70–90% of the 300,000 civilians in the city fled before the attack.[29]

U.S. Army soldiers from TF 2–7 CAV, prepare to enter a building during fighting in Fallujah.

With Navy SEAL and Marine Recon Snipers providing reconnaissance and target marking on the city perimeter, ground operations began on the night of 7 November 2004. Attacking from the west and south, the Iraqi 36th Commando Battalion with their U.S. Army Special Forces advisers, SEAL Sniper Task Elements from Naval Special Warfare Task Group Central and the U.S. Marine Corps Scout Platoon, 1st and 2nd Platoon, Charlie Company, 1st Battalion 9th Infantry Regiment (Manchu), 2nd Brigade Combat Team, 2nd Infantry Division (U.S. Army), 3rd Platoon Alpha Company 2/72nd Tank Battalion (U.S. Army), and 3rd Light Armored Reconnaissance Battalion, reinforced by Bravo Company from the Marine Corps Reserve's 1st Battalion, 23rd Regiment, and supported by Combat Service Support Company 113, from Combat Service Support Battalion 1, captured Fallujah General Hospital, Blackwater Bridge, ING building, and villages opposite of the Euphrates River along Fallujah's western edge.[34] Troops from the 1st Battalion, 3rd Marines fired 81mm mortars in an operation in south Fallujah. The same unit, operating under the command of the U.S. Army III Corps, then moved to the western approaches to the city and secured the Jurf Kas Sukr Bridge.[34] These initial attacks, however, were a diversion intended to distract and confuse the insurgents holding the city.

After Navy Seabees from I MEF Engineer Group (MEG) interrupted and disabled electrical power at two substations located just northeast and northwest of the city, two Marine Regimental Combat Teams, Regimental Combat Team 1 (RCT-1) and Regimental Combat Team 7 (RCT-7) launched an attack along the northern edge of the city. They were joined by two U.S. Army heavy battalion-sized units, the 2nd Battalion, 7th Cavalry Regiment, and Task Force 2nd Battalion, 2nd Infantry Regiment (Mechanized). These two battalions were followed by four infantry battalions who were tasked with clearing the remaining buildings. The Army's mechanized Second Brigade, First Cavalry Division, augmented by the Marines' Second Reconnaissance Battalion and A. Co 1st Battalion, 5th Infantry Regiment, was tasked to infiltrate the city and destroy any fleeing enemy forces.[35] The British Army's 1st Battalion, The Black Watch, patrolled the main highways to the east. The RCTs were augmented by three 7-man SEAL Sniper Teams from Naval Special Warfare Task Group-Central and one platoon from 1st Recon, who provided advance reconnaissance in the city, Joint Terminal Aircraft Control (JTAC) and unilateral overwatch throughout the operation. The United States Air Force provided close air support for the ground offensive, employing F-15 Strike Eagles, F-16 Fighting Falcons, A-10 Thunderbolt IIs, B-52 Stratofortresses, and AC-130 gunships to carry out close-quarter precision airstrikes against enemy strongholds within the city. The Air Force also employed MQ-1 Predator unmanned aerial vehicles for reconnaissance and precision strikes, and the U-2 Dragon Lady high-altitude reconnaissance aircraft for intelligence collection, surveillance and reconnaissance before, during, and after the battle.

The six battalions of Army, Marine and Iraqi forces, aided by the USMC and SEAL Sniper and JTAC elements pre-fire operations, moved into the city under the cover of darkness; and once aligned with the reconnaissance elements, began the assault in the early hours of 8 November 2004, preceded by an intense artillery barrage and air attack. This was followed by an attack on the main train station, which was then used as a staging point for follow-on forces. By that afternoon, under the protection of intense air cover, Marines entered the Hay Naib al-Dubat and al-Naziza districts. The Marines were followed by the Navy Seabees of NMCB 4 and NMCB 23 who bulldozed the streets clear of debris from the bombardment that morning. The Seabees used armored bulldozers to plow the streets while remaining safe and protected from enemy fire. Shortly after nightfall on 9 November 2004, Marines had reportedly reached Phase Line Fran at Highway 10 in the center of the city.

An air strike is called in on a suspected insurgent hideout in Fallujah.

While most of the fighting subsided by 13 November 2004, U.S. Marines and Special Operations Forces continued to face determined isolated resistance from insurgents hidden throughout the city. By 16 November 2004, after nine days of fighting, the Marine command described the action as mopping up pockets of resistance. Sporadic fighting continued until 23 December 2004.

By late January 2005, news reports indicated U.S. combat units were leaving the area, and were assisting the local population in returning to the now heavily damaged city.

U.S. Army soldiers rush a wounded soldier to a waiting U.S. Marine CH-46E Sea Knight helicopter during the Second Battle of Fallujah in November 2004.

The battle proved to be the bloodiest of the war and the bloodiest battle involving American troops since the Vietnam War. Comparisons with the Battle of Hue City and the Pacific campaign of World War II were made.[41] Coalition forces suffered a total of 107 killed and 613 wounded during Operation Phantom Fury. U.S. forces had 54 killed and 425 wounded in the initial attack in November.[10] By 23 December when the operation was officially concluded, the casualty number had risen to 95 killed and 560 wounded.[11] British forces had 4 killed and 10 wounded in two separate attacks in the outskirts of Fallujah.[12][13] Iraqi forces suffered 8 killed and 43 wounded.[10] Estimates of insurgent casualties are complicated by a lack of official figures. Most estimates place the number of insurgents killed at around 1,200[42] to 1,500,[14] with some estimations as high as over 2,000 killed.[10][11] Coalition forces also captured approximately 1,500 insurgents during the operation.[14] The Red Cross estimated directly following the battle that some 800 civilians had been killed during the offensive.[43][44][45][46]

Fallujah suffered extensive damage to residences, mosques, city services, and businesses. The city, once referred to as the "City of Mosques", had over 200 pre-battle mosques of which 60 or so were destroyed in the fighting. Many of these mosques had been used as arms caches and weapon strongpoints by Islamist forces. Of the roughly 50,000 buildings in Fallujah, between 7,000 and 10,000 were estimated to have been destroyed in the offensive and from half to two-thirds of the remaining buildings had notable damage.[48][49]

While pre-offensive inhabitant figures are unreliable, the nominal population was assumed to have been 200,000–350,000. One report states that both offensives, Operation Vigilant Resolve and Operation Phantom Fury, created 200,000 internally displaced persons who are still living elsewhere in Iraq.[50] While damage to mosques was heavy, coalition forces reported that 66 out of the city's 133 mosques had been found to be holding significant amounts of insurgent weaponry.[51]

A city street in Fallujah heavily damaged by the fighting.

In mid-December, residents were allowed to return after undergoing biometric identification, provided they wore their ID cards all the time. Reconstruction progressed slowly and mainly consisted of clearing rubble from heavily damaged areas and reestablishing basic utilities. Only 10% of the pre-offensive inhabitants had returned as of mid-January, and only 30% as of the end of March 2005.[52]

Nevertheless, the battle proved to be less than the decisive engagement that the U.S. military had hoped for. Some of the nonlocal insurgents, along with Zarqawi, were believed to have fled before the military assault, leaving mostly local militants behind. Subsequent U.S. military operations against insurgent positions were ineffective at drawing out insurgents into another open battle, and by September 2006, the situation had deteriorated to the point that the Al-Anbar province that contained Fallujah was reported to be in total insurgent control by the U.S. Marine Corps, with the exception of only pacified Fallujah, but now with an insurgent-plagued Ramadi.[53][54]

After the U.S. military operation of November 2004, the number of insurgent attacks gradually increased in and around the city, and although news reports were often few and far between, several reports of IED attacks on Iraqi troops were reported in the press. Most notable of these attacks was a suicide car bomb attack on 23 June 2005 on a convoy that killed 6 Marines. Thirteen other Marines were injured in the attack. However, fourteen months later insurgents were again able to operate in large numbers.

A third push was mounted from September 2006 and lasted until mid-January 2007. Tactics developed in what has been called the "Third Battle of Fallujah," when applied on a larger scale in Ramadi and the surrounding area, led to what became known as "the Great Sunni Awakening." After four years of bitter fighting, Fallujah was turned over to the Iraqi Forces and the Iraqi Provincial Authority during the autumn of 2007.

In this series of photographs a Marine and Corpsman from 1st Battalion 8th Marines attempt to recover a Marine wounded by a sniper; an insurgent machine-gunner cuts down one of the would be rescuers.[63]

Despite the Coalition success, the battle was not without controversy. A number of allegations have been made regarding the United States' armed intervention. For example, a documentary entitled Fallujah, The Hidden Massacre stated that the U.S. forces used white phosphorus as a weapon against civilians. The U.S. military maintains that white phosphorus was not used against civilians, but has confirmed its use as an incendiary weapon against enemy combatants.[64]

According to the Organization for the Prohibition of Chemical Weapons, white phosphorus is permitted under the Chemical Weapons Convention if it is used to illuminate a battlefield or to produce smoke. But white phosphorus is a banned chemical weapon if its toxic and caustic properties are used intentionally.

An article by a US Army captain present at the battle published in the US Army's Field Artillery Manual makes it clear that white phosphorus was used against insurgents in situations where conventional munitions did not have the desired effects.[65][66]

The use of phosphorus was especially controversial in the United Kingdom because British forces were involved in the battle. British law prohibits British forces being present in a theatre in which phosphorus is used as an anti-personnel weapon, whether or not the targets are military personnel.[67]

On 16 November 2004, NBC News aired footage that showed a U.S. Marine killing a wounded Iraqi fighter. In this video, the Marine was heard saying that the Iraqi was "playing possum". NCIS investigators later determined that the Marine was acting in self-defense.[68] The AP news agency reported that military-age males attempting to flee the city were turned back by the U.S. military.[69]

Occupation: Dreamland, a 2005 documentary film that follows soldiers of the 1/505 of the 82nd Airborne Division in Fallujah, Iraq, in the beginning of 2004.

Shootout! - Episode 1: D-Day: Fallujah (UPC: 733961741353), a 2006 A&E History Channel Special detailing various gun battles that occurred during the Second Battle of Fallujah.

Fear Not the Path of Truth,[70] a 2013 documentary film from a veteran of the 2nd siege of Fallujah who investigates atrocities that he alleges occurred and the legacy of US foreign policy in Fallujah.

Six Days in Fallujah, is a video game that follows a squad of U.S. Marines from 3rd Battalion, 1st Marines over the span of the six bloodiest days in the battle for Fallujah. It was designed with input from active-duty and retired Marines from 3rd Battalion 1st Marines, as well as interviews from the U.S. Marines, Iraqi insurgents, and Iraqi civilians involved in the battle. Currently, the game has no publisher after being dropped by Konami for the controversy surrounding it and remains in limbo.[72]

Close Combat: First to Fight, is a video game that was also designed with input from former and active-duty U.S. Marines from 3rd Battalion, 1st Marines, who had participated in combat around Fallujah, Iraq during Operation Phantom Fury.

Phantom Fury: The 2nd Battle for Fallujah, is a solitaire board game based on the actions of 3rd Battalion, 1st Marine Regiment, 1st Marine Division in the Jolan district in November 2004.[73]